on friday in florida, he staggered through 18 holes on live tv appearing to be in the middle of a medical emergency. >> i thought i was having a heart attack. i felt from the first tee to the 18th. i felt like i was going to pass out but i didn't have a choice. >> reporter: the stakes were huge. his future on the pga tour, his livelihood on the line. >> i told caddy, i said, we're not leaving here until we get carted off from the middle of the fairway or somewhere. >> reporter: no sooner did he finish the round, but the ambulance whisked him away. doctors determined his heart seems to be healthy. this was a panic attack. the sudden onset of extreme anxiety, causing the body to pump out adrenaline as the body's "fight or flight" response kicks in. heart palpitations, sweating, shortness of breath. 6 million american adults suffer from panic disorders. they're symptoms similar to having a heart attack and people fear that they are dying. >> i spent more time worrying about breathing and slowing down. >> reporter: valium and drugs not allowed on the pga tour are other. for now he'll stick to